Questions about cable selection?
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We have two pumps with a total capacity of 110 kilowatts, located 50 meters away from the power distribution room. May I ask what size cable and circuit breaker to choose? What are the selection criteria?
Depending on the way you lay the cables, select the derating factor and then multiply it by the cable’s current-carrying capacity; the result should be greater than the rated current of the 55kW motor. Because the distance is only 50 meters, the cable voltage drop is very small.
What is the rated voltage? If it is 380V, YJV22-3×150+1×70 can be chosen, with 2 cables per unit, and a circuit breaker of 400A should be used. There is no need to consider pressure drop issues.
Could you please provide the selection principles or guidelines?
First, confirm two issues: there is no need to consider pressure drop for 50 meters. What is the operating mode of the two pumps? For example: 1 in use and 1 as backup, allowing short-term shutdowns for pump switching; 1 in use and 1 as backup, no shutdown allowed during pump switching; 1 in use and 1 as backup, both units may be in use under high load conditions, or even both units can remain in the on state. The results are different. I. Select the wiring and switches based on 55kW. A 125 switch and 3*35 cables will suffice. II. For something between I and III, a 250 switch can be chosen. The cable should still be 3*35. Be careful not to run two pumps simultaneously for long periods of time (a few minutes is generally acceptable). III. Select a switch of 250A based on 110kW. 3*95 cable.